1. Field of the Invention:
The invention relates in general to elevator systems, and more specifically to strategy for controlling the operation of a plurality of elevator cars in an elevator system.
2. Description of the Prior Art:
The lower terminal, main floor, or lobby, as it is variously called, requires substantially more wiring and controls than other floors of the building in elevator systems of the prior art. This is due to the main floor demand or quota control, and dispatching functions, usually associated with this floor. For example, dispatching requires the detection of cars at the main floor, the selection of a next car, control of hall lanterns and doors in response thereto, weight of the load in cars at the lobby floor, car calls in the cars located at the lobby floor, and other events which may determine the dispatching of the Next car. The main floor demand function involves car detectors and car counters for counting cars at the main floor and controls to call cars to the main floor to establish and maintain a desired quota.
Elevator systems may have traffic patterns at certain times of the day which make it advantageous to provide quota and dispatching functions at a floor other than the main or lobby floor. For example, garage levels below the main floor may have heavier traffic at certain times of the morning than the lobby floor; a convention floor may have concentrated heavy traffic at any time of the day or night; and, depopulating a building by staggered quitting times may switch heavy traffic from one floor to another on a timed basis. Since the quota and dispatching functions require costly control, any attempt in the prior art to provide such functions is on a very selective and usually partial basis, such as a complicated mixture of two partial lobbies in response to the setting of a switch, which requires additional costly control at the "extra" lobby; and, by a special convention floor feature which requires spotting controls or other costly sensing and quota controls which are required at the convention floor.
It would be desirable to be able to automatically and completely switch the lobby functions, or at least certain of the lobby functions, from one floor to any other floor in the building, and to select the dispatching direction from this floor, due to anticipated or actual traffic demands at a floor, making the normal lobby the same as any other non-lobby floor during the time the lobby functions are switched to another floor, if this could be accomplished without adding additional costly control at each floor of the building.